In a large scale enterprise network infrastructure, when a video stream needs to be transmitted to a large number of client devices via multicast, in order to provide the optimal performance, the network infrastructure usually transmits the video stream to all of the client devices which subscribe to the multicast group in a true multicast mode. In the true multicast mode, no conversion is ever made from multicast transmission to unicast transmission. This would work well when all of the client devices are capable of achieving high performance.
Nevertheless, in reality, not all of the client devices subscribed to a multicast video stream will be high performance client. Some client devices may frequently switch in and out of power save mode. This would lead to poor network performance with increased delays and jitters.
To illustrate the problem, assuming that in the network infrastructure where 50 client devices are associated with an access point and subscribed to receive true multicast video traffic. Further, assuming that the access point has a delivery traffic indication message (DTIM) interval value set to 3 in order to optimize power save for mobile client devices.
In this case, if one of the client devices in the multicast group switches into power save mode, the network would have to buffer the multicast traffic and release it at every DTIM interval, which would be every 300 milliseconds. If the multicast traffic being streamed is a video feed, then the quality of the video will likely deteriorate because of increased delay and jitter. Currently, there is no good solution for handling such multicast client devices that are configured to switch to power save mode frequently while providing high network performance at the same time.